Abstract
A gyro-TWT (traveling wave tube) is often plagued by absolute instabilities in lower order modes and even in the operating mode itself. The authors describe an experimental study of these problems. The experiment is performed in the lowest order mode in a cylindrical waveguide (TE 011 ), using a low-α beam to excite a wave with large k ∥ ). A gyroresonant wiggler partially transforms the axial velocity of a high-quality Pierce beam into transverse velocity. A 100-keV, 5-A, α = 0.5 beam generates 9-GHz RF in 3 kG magnetic field. Magnetic tapering enhances the efficiency. The gain is predicted to be 60 dB with a bandwidth in excess of 20%.